Journal of Geophysics and Engineering, 2009, 6: 386-389

PS-wave Q estimation based on the P-wave Q values

Yun Wang, Jun Lu, Ying Shi and Chun Yang

Abstract

Through assumption of the equivalent velocity and equivalent quality factor of the PS-wave, in visco-elastic media, PS-wave Q estimation can be realized with the P-wave quality factor and P- to S-wave velocity ratio. For sedimentary rock, which has strong agglutination, the internal friction is mainly contributed by the shear friction along crevices or inter-granular crevices, so that a relationship between PS-wave Q values and P-wave Q values can be built up even when the S-wave Q values are unknown. In the estimation of the PS-wave quality factor, the P- to S-wave velocity ratio can be computed based on two-way traveltimes of PP and PS events respectively, in order to avoid the influence of the inaccuracy of P- and S-wave velocities. The method is demonstrated with a zero-offset VSP data in a coal-mining field. The results of P-wave and PS-wave Q values estimated show a consistency with lithology revealed from drilling.